/*
** $Id: lopcodes.h,v 1.148 2014/10/25 11:50:46 roberto Exp $
** Opcodes for Lua virtual machine
** See Copyright Notice in lua.h
*/

#ifndef lopcodes_h
#define lopcodes_h

#include "llimits.h"


/*===========================================================================
  We assume that instructions are unsigned numbers.
  All instructions have an opcode in the first 6 bits.
  Instructions can have the following fields:
    'A' : 8 bits
    'B' : 9 bits
    'C' : 9 bits
    'Ax' : 26 bits ('A', 'B', and 'C' together)
    'Bx' : 18 bits ('B' and 'C' together)
    'sBx' : signed Bx

  A signed argument is represented in excess K; that is, the number
  value is the unsigned value minus K. K is exactly the maximum value
  for that argument (so that -max is represented by 0, and +max is
  represented by 2*max), which is half the maximum for the corresponding
  unsigned argument.
===========================================================================*/


enum OpMode {iABC, iABx, iAsBx, iAx};  /* basic instruction format */


/*
** size and position of opcode arguments.
*/
#define SIZE_C        9
#define SIZE_B        9
#define SIZE_Bx        (SIZE_C + SIZE_B)
#define SIZE_A        8
#define SIZE_Ax        (SIZE_C + SIZE_B + SIZE_A)

#define SIZE_OP        6

#define POS_OP        0
#define POS_A        (POS_OP + SIZE_OP)
#define POS_C        (POS_A + SIZE_A)
#define POS_B        (POS_C + SIZE_C)
#define POS_Bx        POS_C
#define POS_Ax        POS_A


/*
** limits for opcode arguments.
** we use (signed) int to manipulate most arguments,
** so they must fit in LUAI_BITSINT-1 bits (-1 for sign)
*/
#if SIZE_Bx < LUAI_BITSINT-1
#define MAXARG_Bx        ((1<<SIZE_Bx)-1)
#define MAXARG_sBx        (MAXARG_Bx>>1)         /* 'sBx' is signed */
#else
#define MAXARG_Bx        MAX_INT
#define MAXARG_sBx        MAX_INT
#endif

#if SIZE_Ax < LUAI_BITSINT-1
#define MAXARG_Ax    ((1<<SIZE_Ax)-1)
#else
#define MAXARG_Ax    MAX_INT
#endif


#define MAXARG_A        ((1<<SIZE_A)-1)
#define MAXARG_B        ((1<<SIZE_B)-1)
#define MAXARG_C        ((1<<SIZE_C)-1)


/* creates a mask with 'n' 1 bits at position 'p' */
#define MASK1(n,p)    ((~((~(Instruction)0)<<(n)))<<(p))

/* creates a mask with 'n' 0 bits at position 'p' */
#define MASK0(n,p)    (~MASK1(n,p))

/*
** the following macros help to manipulate instructions
*/

#define GET_OPCODE(i)    (cast(OpCode, ((i)>>POS_OP) & MASK1(SIZE_OP,0)))
#define SET_OPCODE(i,o)    ((i) = (((i)&MASK0(SIZE_OP,POS_OP)) | \
        ((cast(Instruction, o)<<POS_OP)&MASK1(SIZE_OP,POS_OP))))

#define getarg(i,pos,size)    (cast(int, ((i)>>pos) & MASK1(size,0)))
#define setarg(i,v,pos,size)    ((i) = (((i)&MASK0(size,pos)) | \
                ((cast(Instruction, v)<<pos)&MASK1(size,pos))))

#define GETARG_A(i)    getarg(i, POS_A, SIZE_A)
#define SETARG_A(i,v)    setarg(i, v, POS_A, SIZE_A)

#define GETARG_B(i)    getarg(i, POS_B, SIZE_B)
#define SETARG_B(i,v)    setarg(i, v, POS_B, SIZE_B)

#define GETARG_C(i)    getarg(i, POS_C, SIZE_C)
#define SETARG_C(i,v)    setarg(i, v, POS_C, SIZE_C)

#define GETARG_Bx(i)    getarg(i, POS_Bx, SIZE_Bx)
#define SETARG_Bx(i,v)    setarg(i, v, POS_Bx, SIZE_Bx)

#define GETARG_Ax(i)    getarg(i, POS_Ax, SIZE_Ax)
#define SETARG_Ax(i,v)    setarg(i, v, POS_Ax, SIZE_Ax)

#define GETARG_sBx(i)    (GETARG_Bx(i)-MAXARG_sBx)
#define SETARG_sBx(i,b)    SETARG_Bx((i),cast(unsigned int, (b)+MAXARG_sBx))


#define CREATE_ABC(o,a,b,c)    ((cast(Instruction, o)<<POS_OP) \
            | (cast(Instruction, a)<<POS_A) \
            | (cast(Instruction, b)<<POS_B) \
            | (cast(Instruction, c)<<POS_C))

#define CREATE_ABx(o,a,bc)    ((cast(Instruction, o)<<POS_OP) \
            | (cast(Instruction, a)<<POS_A) \
            | (cast(Instruction, bc)<<POS_Bx))

#define CREATE_Ax(o,a)        ((cast(Instruction, o)<<POS_OP) \
            | (cast(Instruction, a)<<POS_Ax))


/*
** Macros to operate RK indices
*/

/* this bit 1 means constant (0 means register) */
#define BITRK        (1 << (SIZE_B - 1))

/* test whether value is a constant */
#define ISK(x)        ((x) & BITRK)

/* gets the index of the constant */
#define INDEXK(r)    ((int)(r) & ~BITRK)

#define MAXINDEXRK    (BITRK - 1)

/* code a constant index as a RK value */
#define RKASK(x)    ((x) | BITRK)


/*
** invalid register that fits in 8 bits
*/
#define NO_REG        MAXARG_A


/*
** R(x) - register
** Kst(x) - constant (in constant table)
** RK(x) == if ISK(x) then Kst(INDEXK(x)) else R(x)
*/


/*
** grep "ORDER OP" if you change these enums
*/

typedef enum {
/*----------------------------------------------------------------------
name        args    description
------------------------------------------------------------------------*/
OP_MOVE,/*    A B    R(A) := R(B)                    */
OP_LOADK,/*    A Bx    R(A) := Kst(Bx)                    */
OP_LOADKX,/*    A     R(A) := Kst(extra arg)                */
OP_LOADBOOL,/*    A B C    R(A) := (Bool)B; if (C) pc++            */
OP_LOADNIL,/*    A B    R(A), R(A+1), ..., R(A+B) := nil        */
OP_GETUPVAL,/*    A B    R(A) := UpValue[B]                */

OP_GETTABUP,/*    A B C    R(A) := UpValue[B][RK(C)]            */
OP_GETTABLE,/*    A B C    R(A) := R(B)[RK(C)]                */

OP_SETTABUP,/*    A B C    UpValue[A][RK(B)] := RK(C)            */
OP_SETUPVAL,/*    A B    UpValue[B] := R(A)                */
OP_SETTABLE,/*    A B C    R(A)[RK(B)] := RK(C)                */

OP_NEWTABLE,/*    A B C    R(A) := {} (size = B,C)                */

OP_SELF,/*    A B C    R(A+1) := R(B); R(A) := R(B)[RK(C)]        */

OP_ADD,/*    A B C    R(A) := RK(B) + RK(C)                */
OP_SUB,/*    A B C    R(A) := RK(B) - RK(C)                */
OP_MUL,/*    A B C    R(A) := RK(B) * RK(C)                */
OP_MOD,/*    A B C    R(A) := RK(B) % RK(C)                */
OP_POW,/*    A B C    R(A) := RK(B) ^ RK(C)                */
OP_DIV,/*    A B C    R(A) := RK(B) / RK(C)                */
OP_IDIV,/*    A B C    R(A) := RK(B) // RK(C)                */
OP_BAND,/*    A B C    R(A) := RK(B) & RK(C)                */
OP_BOR,/*    A B C    R(A) := RK(B) | RK(C)                */
OP_BXOR,/*    A B C    R(A) := RK(B) ~ RK(C)                */
OP_SHL,/*    A B C    R(A) := RK(B) << RK(C)                */
OP_SHR,/*    A B C    R(A) := RK(B) >> RK(C)                */
OP_UNM,/*    A B    R(A) := -R(B)                    */
OP_BNOT,/*    A B    R(A) := ~R(B)                    */
OP_NOT,/*    A B    R(A) := not R(B)                */
OP_LEN,/*    A B    R(A) := length of R(B)                */

OP_CONCAT,/*    A B C    R(A) := R(B).. ... ..R(C)            */

OP_JMP,/*    A sBx    pc+=sBx; if (A) close all upvalues >= R(A - 1)    */
OP_EQ,/*    A B C    if ((RK(B) == RK(C)) ~= A) then pc++        */
OP_LT,/*    A B C    if ((RK(B) <  RK(C)) ~= A) then pc++        */
OP_LE,/*    A B C    if ((RK(B) <= RK(C)) ~= A) then pc++        */

OP_TEST,/*    A C    if not (R(A) <=> C) then pc++            */
OP_TESTSET,/*    A B C    if (R(B) <=> C) then R(A) := R(B) else pc++    */

OP_CALL,/*    A B C    R(A), ... ,R(A+C-2) := R(A)(R(A+1), ... ,R(A+B-1)) */
OP_TAILCALL,/*    A B C    return R(A)(R(A+1), ... ,R(A+B-1))        */
OP_RETURN,/*    A B    return R(A), ... ,R(A+B-2)    (see note)    */

OP_FORLOOP,/*    A sBx    R(A)+=R(A+2);
            if R(A) <?= R(A+1) then { pc+=sBx; R(A+3)=R(A) }*/
OP_FORPREP,/*    A sBx    R(A)-=R(A+2); pc+=sBx                */

OP_TFORCALL,/*    A C    R(A+3), ... ,R(A+2+C) := R(A)(R(A+1), R(A+2));    */
OP_TFORLOOP,/*    A sBx    if R(A+1) ~= nil then { R(A)=R(A+1); pc += sBx }*/

OP_SETLIST,/*    A B C    R(A)[(C-1)*FPF+i] := R(A+i), 1 <= i <= B    */

OP_CLOSURE,/*    A Bx    R(A) := closure(KPROTO[Bx])            */

OP_VARARG,/*    A B    R(A), R(A+1), ..., R(A+B-2) = vararg        */

OP_EXTRAARG/*    Ax    extra (larger) argument for previous opcode    */
} OpCode;


#define NUM_OPCODES    (cast(int, OP_EXTRAARG) + 1)



/*===========================================================================
  Notes:
  (*) In OP_CALL, if (B == 0) then B = top. If (C == 0), then 'top' is
  set to last_result+1, so next open instruction (OP_CALL, OP_RETURN,
  OP_SETLIST) may use 'top'.

  (*) In OP_VARARG, if (B == 0) then use actual number of varargs and
  set top (like in OP_CALL with C == 0).

  (*) In OP_RETURN, if (B == 0) then return up to 'top'.

  (*) In OP_SETLIST, if (B == 0) then B = 'top'; if (C == 0) then next
  'instruction' is EXTRAARG(real C).

  (*) In OP_LOADKX, the next 'instruction' is always EXTRAARG.

  (*) For comparisons, A specifies what condition the test should accept
  (true or false).

  (*) All 'skips' (pc++) assume that next instruction is a jump.

===========================================================================*/


/*
** masks for instruction properties. The format is:
** bits 0-1: op mode
** bits 2-3: C arg mode
** bits 4-5: B arg mode
** bit 6: instruction set register A
** bit 7: operator is a test (next instruction must be a jump)
*/

enum OpArgMask {
  OpArgN,  /* argument is not used */
  OpArgU,  /* argument is used */
  OpArgR,  /* argument is a register or a jump offset */
  OpArgK   /* argument is a constant or register/constant */
};

LUAI_DDEC const lu_byte luaP_opmodes[NUM_OPCODES];

#define getOpMode(m)    (cast(enum OpMode, luaP_opmodes[m] & 3))
#define getBMode(m)    (cast(enum OpArgMask, (luaP_opmodes[m] >> 4) & 3))
#define getCMode(m)    (cast(enum OpArgMask, (luaP_opmodes[m] >> 2) & 3))
#define testAMode(m)    (luaP_opmodes[m] & (1 << 6))
#define testTMode(m)    (luaP_opmodes[m] & (1 << 7))


LUAI_DDEC const char *const luaP_opnames[NUM_OPCODES+1];  /* opcode names */


/* number of list items to accumulate before a SETLIST instruction */
#define LFIELDS_PER_FLUSH    50


#endif
